Ok so I am new to this site...sorry in advance if my strife has already been solved several times...
I have a beautiful 2004 Infiniti G35 sedan...she drove beautifully until about a month ago...here's what I have done mechanically to her... I've replaced all rotors and pads and made bled them properly...my fluid is topped off as well...I also replaced the lower control arm bushings with white line bushings... haven't done any modding yet as I am paying her off at a crazy amount a month...

Ok so about a month ago I drove some friends to Kansas city and she drove just fine...we come back after a couple hours and BAM!!! LIMP MODE! ****...limped her home...if you start her up she has the SEC but the VDC and SLIP lights only come on after you rev above somewhere around 2500 rpm...she will accelerate very slowly but after the first complete stop she gains some mysterious horsepower and I can safely cruise around while guzzling gas like no other...she drives okay but she definitely has lost all her torquiness I have come to love...brought it to the Nissan dealership in topeka and they said my ECM was sending a backwards doubled amount of voltage to my apps...codes are P1238/P1228...I have researched this here but I don't know if anyone else has this exact problem as you'll see later on... I'm probably wrong and I'm sorry...

So I bought a parts matching ECU and a reproduction apps (just the sensor not the whole pedal) it fit really tightly...brought it back today and nothing...still the same...

Side notes...I have made her airborne...not intentionally, back roads are a bitch...I have caressed her bottom...only minor dings and scratches...I replaced the drain plug as the formers ring broke...but there still is a decent amount of oil on the pan...I also cleaned the throttle body prior to the test today and it was dirty but not that much considering she has 132000 miles on her...my battery reads 13 with car not running and 15 when started...
PLEASE HELP HER...

 

Why didn't you take it to an Infiniti dealer in the first place?

With a thirteen year old vehicle you need to be financially able to spend money on parts beginning to fail and wear out.

A brand new vehicle comes with all new parts and a warranty

Good luck

Telcoman

 

I've had similar problems on my G35x shortly after buying it used.

Did you or the techs at Nissan perform an ECU reset or Throttle Body reset? Look here in the forums for posts regarding it...there are many. I recommend both. For me, I reset it and the problem didn't reappear.

Another thing: was there any change that you noticed? Different fuel grade, climate, etc? I had noticed that the problem with my car had come up when it was raining/snowing as opposed to clear, dry days.

Also, possibly unrelated, I had changed the passenger side cam shaft position sensor due to some slow start issues happening maybe two months after the ECU and Throttle Body reset. Take note of the minor things, as they will usually point you in the right direction regarding repairs.

 

wakko_99 yes they tried to do the re-learns on the original ecu but it wouldn't accept them or it just didn't fix the problem...so I bought another one and the same thing happened...she starts normally...no it's the same problem rain or shine...I put premium in her and ever since the disaster she literally guzzles fuel...

 

I would suggest taking a look at the engine components to determine if anything is odd.

SInce you changed the ECU to a like one and it didn't work, I would poke around and make sure that sensors are registering correctly and that the hardware doesn't have anything amiss. I'm not well-versed in the timing system on the engine YET, but that would be where I would start to look for things... any sensor related to timing such as the crankshaft and camshaft position sensors, etc. Hook up an OBDII scanner and check the timing advance when revving up the engine.

I don't quite know what the mechanics' comment on the backwards double voltage for the APPS, so I can't help you there.